It’s using unity game engine. I’m a graphics programmer in the industry and at my current and last workplace I made tech for games studios (i.e. I dealt with performance of easily 100 games a year at one point). Unity by far was default the worst to deal with due to the limited tools to fix issues that were inherint to the engine. Note don’t take this as me saying unity is a bad engine, it’s just that it isn’t a performant one. Its focus is elsewhere (accessibility and ease of development, things it excels at).

So yes, you can definitely assume that, in fact I’d assume one core for the simulation unless they wrote an entire new architecture to replace unity’s functionality (you’d still be locked to single thread sync points, but that’s manageable). It’s a hassle most don’t deal with as it’s a lot of work to struggle against writing code like unity wants you to write it.

I worked in a studio that exactly did that a decade ago, and it was painful and frankly a huge upfront dev cost that takes a long time to pay off.